Shibumi is a novel published in 1979, written in English by Trevanian, a pseudonym of Rodney William Whitaker, an American academic who remained mysterious throughout most of his life. Shibumi is set in the 1970s and details the struggle between the "Mother Company", a conspiracy of energy companies that secretly controls much of the western world, and a highly skilled assassin, Nicholaï Hel.

Nicholaï Hel is an assassin, born in Shanghai in the 1930s and raised in a cosmopolitan fashion by his mother, a deposed member of the Russian aristocracy, and a general in the Japanese Imperial Army who has been billeted in Nicholaï's mansion. Under the general, Hel is introduced to the concept of shibumi and the game Go, eventually being sent to Japan, where he trains under a famous master of the game and becomes 'culturally Japanese'. The master of this school discovers Nicholai's ability to mentally escape from reality and come back rested and refreshed. When Japan surrenders in 1945, Hel, after long months of hunger, finds (thanks to his knowledge of many languages) a job as an interpreter in the US Occupation Army and becomes a decoder agent in United States Intelligence.

Hel learns that the general who raised him is being held as a prisoner of war by the Russians and faces an ignominious show-trial for war crimes, and decides that the only way he can show his gratitude for the man's raising him in Shanghai is to kill him and help him avoid the embarrassment of the trial. He achieves this through his skills at the art of "Naked/Kill", a martial discipline that trains in the use of ordinary items as instruments of death. After Hel kills the general he is turned over to the American occupation force. Hel is then tortured by the Americans and held in solitary confinement without trial, Hel being a citizen of no country. In prison, his physical and mental discipline, along with studying the Basque language from some old books abandoned by a missionary, help him to retain his sanity, although, due to the torture and drugs used in his interrogation, he is no longer able to fully escape mentally and reach his state of peaceful ecstasy. He even develops, in his solitude, a "proximity sense" through which he is aware of any being drawing near (along with its amicable or hostile intentions), and which also allows him to find his way in complete darkness.

After three years, Hel is recruited out of his cell by the US Intelligence Service. It is in desperate need of an agent able to cause severe discord between Russia and China. It needs someone who has nothing to lose, who has European features, and who can speak fluent Chinese and Russian. Hel succeeds in his mission, taking for payment the names and locations of those who tortured him, and goes on to become one of the highest-paid and most skillful assassins in the world.

The novel begins with Hel, retired in his late fifties in a small castle overlooking a village of the Haute-Soule, in the mountainous Northern Basque Country. He is an honorary member of the local Basque population, and his best friend among them is Beñat Le Cagot, a truculent Basque nationalist and bard, with whom he shares an immense love for freedom and an addiction to spelunking. Hel thinks he is now allowed to enjoy life in a shibui way (mingling discreet epicureanism with fatalism and detachment) and he slowly improves his Japanese garden, enjoys restrictive gastronomy, and practices highly esoteric sex with his concubine.

Hel's shibumi existence is interrupted by the arrival of the niece of a man who saved Hel's life many years ago, herself the only survivor of a Jewish commando unit that took up arms to terminate the last of the Black September terrorists, the rest of the small unit having been gunned down in an Italian airport by CIA agents. She begs Hel to help her finish her mission and eliminate the terrorists, and gain revenge on the Mother Company.

Shibumi is, broadly, a parody of the spy novel genre, but Trevanian also incorporated pieces of philosophy and highly specific cultural observations in the work, most obviously with his portrayals of American (and, more generally, western) culture after World War II. Trevanian himself echoed his hero Hel's dislike of western materialism in the few interviews he gave to the press.

The book contains 6 chapters of unequal length, each of them bearing the name of a go game figure:

Fuseki: The opening stage of a game when the entire board is taken into account.

Sabaki: An attempt to dispose of a troublesome situation in a quick and flexible way.

Seki: A neutral situation in which neither side has the advantage. A "Mexican stand-off."

Uttegae: A sacrifice play, a gambit.

Shicho: A running attack.

Tsuru no Sugomori: "The confinement of the cranes to their nest," a graceful maneuver in which the enemy stones are captured.

Trevanian's (Whitaker's) character Hel was supposed, in the novel, to have written an analysis of Go which was in fact a spoof of the game. In the book-within-a-book, the commentator's attempts to attach spurious significance of life and philosophy to what were, in fact, clumsy and amateurish maneuvers was a part of the satire. The use of subtly mis-stated Go figures to rationalize the structure of a novel that was in itself a spoof of the highly rationalized incompetence of people who believe they run the world is an indisposable pillar of the satire.